Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
  • B01J29/20—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type containing iron group metals, noble metals or copper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
  • C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
  • C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
  • C07C5/2708—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with crystalline alumino-silicates, e.g. molecular sieves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/10—After treatment, characterised by the effect to be obtained
  • B01J2229/16—After treatment, characterised by the effect to be obtained to increase the Si/Al ratio; Dealumination
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S423/00—Chemistry of inorganic compounds
  • Y10S423/25—Mordenite, e.g. NA-D, pttilolite, zeolon

Definitions

• catalysts comprising crystalline zeolitic alumino-silicates with and without hydrogenation promoters. See, for example, U.S. 3,140,252 and U.S. 3,190,939. While catalysts have now been discovered which give excellent results in isomerization as well as in other hydroconversion reaction improvements in the art are not only possible, but supported by sufiicient economic incentive.
• the catalyst disclosed therein is a particular form of a crystalline zeolite known as mordenite which is converted from the sodium form to the acid or H form.
• mordenite is a naturally occuring mineral, a syn- 3,475,345 Patented Oct. 28, 1969 ice thetic mordenite is available commercially from the Norton Company and marketed under the name Zeolon.
• the present invention is an improved catalyst based on the use of a specially treated mordenite having a hydrogenation metal incorporated thereon by ion-exchange and in one embodiment subjected to a special calcination proedur-e.
• Mordenite is characterized by its high silicon to aluminum ratio of about 5:1 and its crystal structure.
• Compositions of mordenite as given in Kirk Othmer, Encyclopedia of Chemical Technology, vol. 12, p. 297, is (Ca, Na )Al Si O 6H O.
• the proposed structure is one in which the basic building block is a tetrahedron consisting of one silicon or aluminum atom surrounded by four oxygen atoms. The crystal is made up of chains of fourand five-membered rings of these tetrahedra.
• Conversion of the sodium form to the hydrogen form is achieved either by the direct replacement of sodium ions with hydrogen ions or by replacement of sodium ions with ammonium ions followed by decomposition of the ammonium form by calcination. At least about and preferably at least about 99%, of the alkali metal is removed by the ion-exchange. Chemical analysis of the calcined product of the ammonium form of mordenite shows that complete decomposition of the ammonium ion has occurred, yet the X-ray pattern of the product is the same as that of the original ammonium form. Thus, no attack on the crystalline alumino-silicate lattice is detected.
• calcination of the ammonium form of other zeolites destroys the crystalline alumino-silicate lattice.
• zeolites such as erionite and X faujasite
• M represents exchangeable alkaline and alkaline earth metal ions
• X-ray diffraction films of the product before and after calcination in air at 932 F. indicate that most of the crystalline alumino-silicate lattice is destroyed during calcination to form amorphous material.
• a synthetic faujasite denoted as 13X by the manufacturer, Linde Company, and having the formula Na Al Si O can be converted to the ammonium form.
• X-ray examination of the decomposition product of the ammonium form of this faujasite shows that extensive destruction of the lattice occurs in this case also. Again, amorphous material is formed.
• the invention is a three-step treatment of sodium mordenite comprising (a) a hot acid treatment, (b) a cold acid treatment followed by (c) treatment with an ammonium compound.
• the metal is incorporated on the triple treated mordenite by ion-exchange from an ammoniacal complex solution, the resulting catalyst composite having improved selectivity and activity.
• the calcination schedule involves heating the catalyst composite in air to a temperature of about 660 F. and then to about 1020 F. in two steps rather than a single step calcination at about 550 C. which is customary.
• both organic or inorganic acids can be used, strong acids being preferred.
• acids which are particularly suitable are strong mineral acids such as H PO H 80 HNO and HCl.
• HCl is especially suitable and is the preferred acid for the practice of the invention in both the hot and cold treating steps.
• aqueous solutions of the acid are preferred. The concentrations may vary over a broad range from 0.1- N. It is convenient and especially preferred to use an acid in aqueous solution of 2 N concentration.
• the temperature preferred is about the boiling temperature of the acid solution. Temperatures in the range of about ZOO-300 F. are contemplated.
• the cold acid treatment is conducted at a temperature from about 50-100 F. and preferably at ambient temperatures.
• the ammonium compound treating step is carried out with any ammonium compound which can form ammonium ions.
• aqueous solutions of neutral nonacidic ammonium compounds are preferred, especially inorganic ammonium compounds such as NH OH, NH Cl, NH sulfates, NH phosphates and NH NO NH NO is preferred.
• Concentration of the ammonium compound is not especially critical and can vary from .1 to 5 M. However, it is preferred to use a solution of about 1 M concentration. Temperature of the ammonium compound treatment can vary over a range of 32-300 F. It is preferred that a hot solution of ammonium compound be used, i.e., a solution at about the boiling temperature.
• Metal is incorporated on the mordenite from any solution in which the metal can exist in the cationic form.
• the use of cationic metal results in ion-exchange of the metal for ammonium ions in the mordenite and is preferred over impregnation with a compound in which the metal exists in the anionic state.
• ammoniacal solutions wherein the metal exists in the form of a cationic complex.
• the dehydrogenation metal be a Group VIII metal and particularly a noble metal component and especially preferred that the metal be palladium.
• the amount of metal incorporated in the catalyst should be at least about 0.05% w. basis finished catalyst and not exceeding about 5 w. It is preferred that the metal content be at least about 0.1% w. and not over 1.5% w.
• the time required for each of the treating steps in the procedure according to the invention will depend upon concentration, temperature and contacting efliciency.
• the hot acid treatment should be continued for at least 30 minutes and preferably from 1-2 hours. No particular advantage is apparent for increased contact time.
• the cold acid treatment requires less time; usually -60 minutes will suffice. Longer times can be used, but are of no particular advantage.
• Treatment with the ammonium compound should be conducted for at least 30 minutes if hot solution is used. If cold ammonium solution is used multiple treatments for extended time are required, for example, final washes for a total of -30 hours. With boiling ammonium compound solutions it is preferred to treat the catalyst for 1-2 hours.
• the hot acid treatment is very effective in removing sodium and greatly reduces the time required for substantial sodium removal. Moreover, the use of hot acid is probably effective in loosening tenaciously held sodium which would not be easily removed by a milder, low temperature acid or ammonium compound treatment. Thus, the hot acid treatment is highly desirable for effective and rapid sodium removal. However, it is believed that treatment with hot acid also dissolves or loosens some of the aluminum ions from the alumino-silicate structure and that the aluminum ions thus loosened tend to clog the ion-exchange sites thereby reducing the effectiveness of the hydrogenation metal incorporation.
• Treatment with cold acid acts to remove these interfering aluminum ions.
• Treatment with ammonium compounds serves two functions; removal of the final traces of sodium, and enhanced ion-exchange ability. Acid treatment often leaves traces of sodium.
• Treatment with ammonium compounds is effective for substantially complete sodium removal. Moreover, the treatment with ammonium leaves ammonium ions in the catalyst ion-exchange sites which readily exchange with the palladium cations.
• each step in the treatment serves a special function which in combination with the other steps results in a superior catalyst.
• Calcination of the finished catalyst composite by the two-step calcination sequence reduces the tendency for destruction of the catalyst and results in a more effective removal of water and ammonia impurities without impairing the metal/mordenite coordination which gives rise to catalytic activity.
• Catalysts prepared in accord with the invention are particularly suitable for isomerization of normal paraflins having 4 through 7 carbon atoms per molecule.
• Feed to an isomerization process using catalysts of the invention can be a substantially pure normal paraffin having from 4 through 7 carbon atoms, mixtures of such normal paraflins, or hydrocarbon fractions rich in such normal paraffins.
• Suitable hydrocarbon fractions are the C to C straight-run fractions of petroleum.
• the process of the invention is conducted at a temperature in the range from about 400 to 650 F. and preferably from about 450 to 600 F. At lower temperatures, conversion of normal paraifins is generally too ilOW to be practical, although selectivity to isoparaifins is substantially At higher temperatures, conversion of normal paraliins is quite high; however, excessive cracking is encountered and selectivity to isoparaffin is extremely low as a result.
• the isomerization reaction can be conducted over a wide range of space velocities, but in general the space velocity is in the range from about 0.5 to 10 and preferably from about 1 to 5. In general, conversion of normal paraflins decreases With an increase in space velocity, although selectivity to the isoparaflin is increased.
• Space velocity refers to WHSV and is expressed as weight of feed per hour per unit weight of catalyst.
• the isomen'zation reaction is carried out in the presence of hydrogen; however, there is little or no net consumption of hydrogen in the process. Any consumption of hydrogen is the result of hydrocracking reactions and it is preferred to keep such reactions to a minimum.
• the function of the hydrogen is primarily to improve catalyst life, apparently by preventing polymerization of intermediate reaction products which would otherwise polymerize and deposit on the catalyst.
• a hydrogen to oil mole ratio of from about 1:1 to :1 and preferably from about 2:1 to 15:1 is used. It is not necessary to employ pure hydrogen since hydrogen-containing gases, e.g., hydrogen-rich gas from the catalytic reforming of naphthas, are suitable.
• Total pressure is in the range from about atmospheric to 1000 pounds per square inch gauge (p.s.i.g.) and preferably from about 300 to 750 p.s.i.g.
• a quantity of the sodium form of synthetic mordenite powder, such as is available from Norton Company is subjected to the following treatments.
• the mordenite powder is placed in a suitable vessel with a 2 N solution of HCl in an amount to just cover the powder.
• the solution is boiled, with stirring, for 1 hour.
• the I-ICl is drained oiI, the powder washed with distilled water and stirred with an equal amount of 2 N HCl solution for minutes at ambient temperature.
• the HCl is again drained oif, the mordenite washed with distilled Water and the mordenite powder mixed with a solution of NH NO of 2 N concentration.
• the solution is boiled for 1-2 hours.
• the treated powder is washed with distilled water until no ammonium ions are detected in the wash water.
• An ammoniacal palladium chloride solution is prepared by the addition of excess ammonium hydroxide to an acidified solution of palladium chloride.
• the treated mordenite powder is stirred with the ammoniacal palladium for 1 hour, washed, dried and formed into pellets or pills.
• Calcination in air is carried out by placing the resulting catalyst in a furnace and raising the temperature to 662 F.
• the catalyst is held at 662 F. for 2 hours and the temperature then raised to 1022" F. where it is maintained for 16 hours.
• the catalyst is then ready for use in isomerization reactions.
• Hot treatment with solutions of HCl or an ammonium salt denotes'digestion of the support for 1 hour in boiling solution.
• Cold HCl treatment is carried out by stirring the support in 2 N HCl for 30 minutes at room temperature.
• the cold NH NO treatment consists of repeated equilibration with five fresh portions of 1 M NH NO at rom temperature over a period of 32 hours.
• each catalyst was prepared by contacting the support with an appropriate quantity of metal reagent.
• the ammoniacal platinum chloride was prepared by addition of excess ammonium hydroxide to chloroplatinic acid. (The orange precipitate of ammonium chloroplatinate that is initially formed dissolves to form a platinum-amine complex when the suspension is heated to boiling.)
• Ammoniacal palladium chloride was similarly prepared by addition of excess ammonium hydroxide to an acidified solution of palladium chloride. Ammoniacal solutions were used because the noble metal is in the form of a cationic complex in these reagents, and can thus be incorporated by ion-exchange. Mordenite used for the test was a powdered form of Na-Zeolon obtained from Norton Company.
• the triple treatment sequence of the invention greatly improves catalyst activity. Comparing Catalysts B and C shows the direct etfect of the three-part treating sequence. Comparison of Catalysts A and B shows the advantage of using palladium, wherein with only half the metal content the palladium catalyst shows nearly the same isomerization performance. It is also noteworthy that palladium is about /3 the cost of platinum. Comparison of Catalysts C and D shows the eiTect of metal content for catalyst prepared according to the invention.
• a method of preparing a paratlin isomerization catalyst which comprises subjecting a crystalline mordenite to a sequential treatment with (a) hot acid, (b) cold acid,

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• Materials Engineering (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catalysts (AREA)
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Cited By (8)

Citations (5)

• 1967
  • 1967-06-07 US US644072A patent/US3475345A/en not_active Expired - Lifetime
• 1968
  • 1968-06-05 NL NL6807837.A patent/NL159017B/xx unknown
  • 1968-06-05 DE DE1767692A patent/DE1767692C3/de not_active Expired
• 1979
  • 1979-10-17 JP JP13305079A patent/JPS5648206B1/ja active Pending

Patent Citations (5)

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